1. Introduction

This Notebook looks at evidence for "portrait" or medallion copying/making lathes from the 17th century considered as precursors to the later single-arm pantographs introduced in the late 18th century as die sinking machines ("reducing engines") for coining.

So far I can only discover evidence of these 17th century machines through instances of their work which have survived. I have found no information about the machines themselves. That these items were mechanically cut typically is assumed in the literature, but I know of no technical study to confirm this (e.g., one which looks at tooling marks microscopically). Writers tend to assume or assert that such lathes were common, but offer no evidence.

It is interesting to note the negative information here. There is no mention of any portrait or medallion lathe in any of the texts on complex or ornamental turning from this period: nothing in Besson (1578), de Caus (1615), Grollier de Servière, Moxon (1678 N.S. - 1680), or Plumier (1701). There is no mention of any such machine in Woodbury's History of the Lathe to 1850 (1961). Note that de la Condamine's work (1734), which was included in the second edition of Plumier (1749), while often casually claimed to describe portrait or medallion lathes of this kind, is actually (a) a machine-tool simulator along with (b) a generator of profiles from arbitrary curves. Condamine's work is astonishing and is important to the pre-history of computing and CNC machine tools, but it is not relevant here.

2. Senger (1677)

In the Museo degli Argenti in the Pitti Palace, Florence, there is preserved a "Double Medallion with a Portrait of Cosimo III and His Monograph." This consists of two ivory medallions joined with an ivory chain (the whole, including the chain, cut from a single piece of ivory). Mosco dates this object to some point after 1670 (probably 1677) and feels that because of its "technical precision" it implies "the use of a pantograph" {Mosco 2004}, p. 153. It is illustrated in {Mosco 2004}, p. 154, and identified there as by Filippo Senger ("or Sengher"). Inventory Number: "Bg. [Bargello] 1879 no. 81."

Brookes is of the opinion that this double medallion was turned on a medallion lathe. It is the earliest item in his list of ``landmarks'' in the history of medallion turning. {Brookes 1991}, p. 174.

I am aware of no information on the machine, if any, used to produce this object or of any technical analysis of it which would confirm or refute its production on a medallion lathe.

3. Landgrave Carl of Hesse-Kassel (by 1688)

{Brookes 1991}, p. 174, says in his summary of the history of medallion turning that in 1688 "Landgrave Carl of Hesse-Kassel was producing medallions" [presumably with a medallion lathe]. At present I have no further details.

4. References

{Brookes 1991} Brookes, E. M. ``Medallion Turning: Some Notes by E. M. Brookes.'' \textit{The Bulletin of the Society of Ornamental Turners.} Vol. 17, Whole No. 84 (Spring 1991): 174-178.

The early numbers of the Bulletin of the Society of Ornamental Turners are available in digital form to members of the S.O.T.

{Mosco 2004} Mosco, Marilena and Ornella Casazza. The Museo degli Argenti: Collections and Collectors. Florence, Italy: Giunti Editore, 2004.

The chapter by Mosco, "Cosimo III and 'Gran Principe' Ferdinando: From Sacred to Profane" (pp. 152-167), is the one illustrating the circa 1677 double medallion probably engraved by machine.